sort of stumble at idle

[gmjunkie]

Well,heres my way of thinking on the project!! But I'm no Rocket Scientist!! But I use a thermal gun allot to see what individual cylinders are doing and yes to see exhaust temps from side to side and where the exhaust system is running the Hottest!! It has helped me determine restrictions in the exhaust systems!! For Instance,THAT POS Ford Expedition of my son in-laws,(I won't Normally work on Fords,But I'm really not NORMAL anyway!!Just ask anybody that really knows me!!) Anyway,Lee had taken it to Billy Mac's by the tracks,Precision Tune,and then to a Ford Dealer (They charged him about $950. Parts and Labor and determined that the cam was worn out!)and spent a Gaggle of $$$$ on it and it helped and ran better for a while!! It ran good cold,but the farther he drove it at higher speeds the worse it would run!! Finlay Chris loaded up Flo(The Grand Daughter!) and came up here for the weekend!! Saturday morning I put snappy on it and it was full of all sorts of codes including Random Miss-Fire 4,5,6,7,8,so I started looking things over and pulling coils,plugs,(1,2,3 plugs looked great#4 was Black and Sooty)(5,6,7,8 plugs looked lean as hell) compression tests between the cylinders was acceptable,Checked ohm-age on injectors and was fine(5.4 Ford you have to pull the fuel rails and 2 injectors on each side anyway to get the plugs out!!)I replaced #4 coil (Tested bad with Ohm Meter)and all the boots and put it back together!! Ran great,checked temps on exhaust and it was all purdy even!!Went for a ride to Spruce Pine and back, and on the way back it started Bucking,Popping,Farting,No Power and running Like the POS it is!! Got home and got out the Thermal Gun and started sooting things!!(Wanted to use the Big Shiny 357!!) Rt Pre-Cat about 400 deg,Rt Cat about 490,Lt Pre-Cat about 500-550,Lt Cat about 850!! Cut that sucker off and stuck a piece of flex pipe in it and went for a drive and it ran like a Raped Ape even after 50 miles!!!Monday morning went to the parts store and got a universal cat and welded it in,and had her back home in Charlotte before she had to go to work at 5:30!! I told Chris that we needed to change the other side the next time she came up so it would have the exact back pressure!! She said she would tell Lee,But if it was running right he'd never do nothing!!:bash:bash:bash

PS Never change plugs in a 5.4 Ford Truck!! They SUCK!!

 

[Toms007]

OK Jesse, you've convinced me to purchase an IR Thermometer. But it will be a few days before I can get someplace to buy one. What should those cats run...temperature wise. Are there any other tale-tell signs? If the weather clears up here, I'm going to go ahead and swap back to the OE injectors as well.

 

[Toms007]

Also the 94 has three O2 sensors,, right? But only two of them count? What's the third one for?

 

[gmjunkie]

Also the 94 has three O2 sensors,, right? But only two of them count? What's the third one for?

Yes,I think mine has 3,1 in front of each pre converter,1 behind rear converter Tom!!(I was thinking OBDII for a minute,and had to Think!! ) The one behind really don't do anything much except monitor what the end result is and Trip a light if things aren't right!!I'd bet that the auto mechanics department at your school will have one!!

PS You can fined one cheaper,I just dug that one off google to show you what I was talking about!! I think mine came from some off the wall tool man that came in here!!I really can't remember,but I think it was around $80.00 and the Max temp is 1200 deg!!

 

[Toms007]

I just talked to our auto instructor and he says 'Sure we've got one", so I'll get it and do some checking. He also says that it makes sense and I should check it.

 

[Toms007]

If I don't get this figured out I am taking it to my stand-by mechanic on the 20th. We talked for about 30 minutes yesterday and he says he'll take a look at it.

 

[LT4man]

Your right (passenger) side has Block Learn values of 152. (See post #136 & #137 above) These values should be equal to the left side Block Learn values.

Also, your right side injector pulse width is too high. That should be equal to the left side injector pulse width.

Your problem lies on the right side of the engine. You might have a stuck fuel injector on that side. The catalytic converter on that side might be partially clogged.

Either of these two scenarios would make your engine run with the 13 in. of vacuum you showed previously. I guarantee you, once you fix your problem, your engine will be running with 15-17 in. of vacuum.

You can test the temperature of all your catalytic converters with an IR thermometer. Any one of them which is substantially hotter than the others would be the problem one.

You can also point the IR thermometer at the individual exhaust manifold ports from on top. Your left side exhaust manifold ports will be running much cooler than your right side exhaust manifold ports. If you find just one port on the right running extremely hot: THAT is your clogged fuel injector!

Keep in touch with me, Tom, and let me know what you find!

Also, are you still throwing the DTC 43? Or did the code go away?

SAVE THE GOSH DARN

 

[Toms007]

Gregory, all that makes sense. I will have to find time to do some checking...and this week doesn't look too good. I just got home from a long day and I have things going on almost every night this week. I'll keep you all posted.

 

[Toms007]

Oh, Gregory, the code 43 still persists....only in the history, but the SES light is still on, and that is the only code that shows (either current or history), so I guess I still have that issue.

I am going to try and work on doing some checking tonight.

 

[gmjunkie]

Oh, Gregory, the code 43 still persists....only in the history, but the SES light is still on, and that is the only code that shows (either current or history), so I guess I still have that issue.

I am going to try and work on doing some checking tonight.

Tom,take a volt ohm meter (Set to AC Voltage to the Big Red wire on the back while running!!) and see if you have any AC Voltage slipping past the diodes in the alternator!! Really shouldn't have any,but 1-1 1/2 vac isn't uncommon and usually won't effect the ECM much,but it can!!

 

[Toms007]

Ok, I was able to get my work done pretty quick after sschool today and I got the IR thermometer. Here's the results of soeme testing

Coolant temp (from digital gauge) 196
Oil Temp (from Digital gauge) 165

Left Cat (measured from about 6" away aimed at the front) 300-310
Right Cat (measured just like the left) 175-185

I also measured the injectors themselves.

1-7 measured from 100-108
2-6 measured from 105-109
#8 measured 130

Exhaust ports
left bank 280-300
right bank 280-300 except #8 360

It appears that I have an issue with #8, I am going to pull the plug on #8 and see if I can see anything.

The SES light has not been on yet today, but Junk, I will check the big red cable when I go back out.

 

[LT4man]

BINGO!!!!!!!!!!

See what you found out with the simple IR thermometer!!!

I was looking for a number that was not in sync!

The right side converter is running cooler than the left because the #8 cylinder is not firing properly and not turning the mixture into a hot explosion to cause the converter to run at the correct temperature.

You are so close to your fix I can almost taste it!

DON'T FORGET TO SAVE THE

 

[Toms007]

OK, so what kind of issue am I looking for? Remember this whole thing started back with a miss at idle under load, that I eventually found the loose spark plug (#8). I tightened it back up and thought (at the time), I have fixed the problem.


So what could the issue be now? Bad plug? Bad injector?

 

[LT4man]

I believe the #8 fuel injector is suspect.

A very quick test would be to swap the #8 spark plug with any other spark plug.

If you get the same exact temperature readings as you did earlier, the fuel injector is at fault.

The right side injector pulses & block learn values were not matching up with the left side.

Even tho the LT1 engine is a Sequential Fuel Injected engine, the PCM does not break down each individual cylinder. Hence we must use our noggin to come up with the answer.

NOW WILL SOMEONE PUHLEASE SAVE THE ?

 

[gmjunkie]

I believe the #8 fuel injector is suspect.

A very quick test would be to swap the #8 spark plug with any other spark plug.

If you get the same exact temperature readings as you did earlier, the fuel injector is at fault.

The right side injector pulses & block learn values were not matching up with the left side.

Even tho the LT1 engine is a Sequential Fuel Injected engine, the PCM does not break down each individual cylinder. Hence we must use our noggin to come up with the answer.

NOW WILL SOMEONE PUHLEASE SAVE THE ?

You could also move the #8 injector to say # 4 and see whats up if the plug doesn't change anything!! Also run a compression check on #8 while your there!!Wouldn't hurt to check the resistance on #8 plug wire either!!

 

[Toms007]

Alright, I swapped #8 and # 4 plugs. #8 looked more black/sooty (probably from when it wasn't tight) #4 looked more "normal". Fired it up and warmed it back up. Most temp readings were very similar. I am suspecting the fuel injector, but will hold judgment until I let it cool down some and I change the #8 injector to some other hole and see if the temps follow.

Junk, I did test the red wire it was giving me about 1/2 a volt AC. I don't have a compression testing gauge...I'll borrow one from school tomorrow. What should the resistance be on the #8 plug wire? I'll check that too once it cools off a bit.

BTW Thanks for the help here guys.

 

[Toms007]

Swapped #8 injector with #1. The Temp readings are still similar.

Left cat 240
rt cat 160

Injectors nearly the same #8 is now running a bit cooler (120) but still hotter than the other injectors (from 7-13*) and #1 (was #8) is running a bit warmer than it was (116 vs 109).

Any ideas what this all means, heck I thought we might have had it figured out, but this doesn't add up.

 

[Toms007]

Alright after letting it really warm up (after swapping #8 and #1 injectors) I took some more temps.

Both cats are about the same temp 340-350 range. #8 injector still a few degrees warmer (3-8 than the rest) #1 Injector running a little warmer than before. I also decided to run another scan to see what the engine was doing. Here are the results.

Desired Idle (RPM) 625 625 625 625 625 625 625 625 625 625 625 625 625 625 625 625 625 625
Engine RPM (RPM) 2125 2125 2075 2075 2100 2125 2100 2100 2100 2100 2125 2125 2125 2100 2175 2175 2150 2150
Coolant Temp (°F) 196.2 196.2 196.2 196.2 196.2 194.9 194.9 194.9 194.9 194.9 194.9 194.9 194.9 194.9 194.9 194.9 194.9 194.9
Oil Temp (°F) 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 190.8 190.8
Manifold Air Tmp (°F) 89.6 89.6 89.6 89.6 89.6 89.6 89.6 88.2 88.2 88.2 88.2 88.2 86.9 86.9 86.9 86.9 86.9 86.9
A/C Pressure (PSI) 84 84 84 84 84 84 84 84 84 84 84 84 84 84 84 84 84 84
MAP Sensor (Volts) 0.78 0.78 0.8 0.8 0.82 0.78 0.82 0.8 0.8 0.82 0.82 0.82 0.76 0.78 0.78 0.78 0.74 0.74
Throttle Sensor (Volts) 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76
Throttle Angle (%) 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5
Battery Voltage (Volts) 13.6 13.6 13.5 13.5 13.6 13.6 13.6 13.6 13.6 13.6 13.6 13.6 13.5 13.6 13.6 13.6 13.6 13.5
Barometric Press (Volts) 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44
Left O2 Sensor (mVolts) 440 440 193 123 114 127 114 118 127 484 96 96 167 110 721 721 127 127
Right O2 Sensor (mVolts) 616 616 668 259 699 492 303 677 655 651 57 57 110 66 57 57 783 686
Block Learn Cell 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17
Left Block Learn value 133 133 133 133 133 133 133 133 133 133 133 133 133 133 133 133 133 133
Right Block Learn value 134 134 134 134 134 134 134 134 134 134 134 134 134 134 134 134 134 134
Left Integrator value 128 128 131 131 131 132 132 132 132 126 132 132 132 132 126 126 132 132
Right Integrator value 138 138 138 144 139 139 144 139 139 136 137 137 135 134 132 132 128 127
Left Inj Pulse (mS) 3 3 3.1 3.1 3.1 3.1 2.9 3.1 2.9 3.1 2.9 2.9 3 2.8 3 3 3 3
Injector Pulse (mS) 3.2 3.2 3.4 3.4 3.3 3.3 3.2 3.3 3.2 3.2 3.2 3.2 3.1 3.1 3 3 2.8 2.9
Mass Air Flow (gr/sec) 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15
CCP Duty Cycle (%) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Idle Air Mtr Pos (steps) 13 13 13 13 13 13 13 13 13 13 13 13 13 13 13 13 13 13
Learned Idle Pos (steps) 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10
Spark Advance (°) 36 36 36 36 36 36 36 36 36 36 36 36 36 36 36 36 36 36
Knock Retard (°) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Knock Sensor 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32
EGR Duty Cycle (%) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Vehicle Speed (MPH) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Engine Run Time (seconds) 122 122 123 124 125 126 127 128 130 131 132 132 133 134 135 135 136 137





































I think that I have gotten some improvement, it seems to be running a bit better (as the numbers on the scan indicate). The next order of business is to swap the original injectors back in to the engine and see what difference that will make. I am keeping my fingers crossed.

 

[gmjunkie]

Junk, I did test the red wire it was giving me about 1/2 a volt AC. I don't have a compression testing gauge...I'll borrow one from school tomorrow. What should the resistance be on the #8 plug wire? I'll check that too once it cools off a bit.

BTW Thanks for the help here guys.

You have no problem with the alternator with 1/2 volt AC!! Much more than 1 1/2 -2 v may be a problem,But you don't have a problem there with 1/2 volt AC!!
As far as the resistance on the wire it will depend on the length,but mine on my 94 is about 1460 ohms and it's a original,If over 1800-1900 ohms,I'd suspect the wire!! Both my cats are running 358*- 402* back and forth after 20-30 minutes of idle!!
I wish I knew how to file and post my scan so we could try to compare them!!
I'm going to Print yours and then go out try to do that!!
Unfortunately my memory is allot shorter than my Unit anymore!!

 

[LT4man]

Alright after letting it really warm up (after swapping #8 and #1 injectors) I took some more temps.

Both cats are about the same temp 340-350 range. #8 injector still a few degrees warmer (3-8 than the rest) #1 Injector running a little warmer than before. I also decided to run another scan to see what the engine was doing. Here are the results.

Desired Idle (RPM) 625 625 625 625 625 625 625 625 625 625 625 625 625 625 625 625 625 625
Engine RPM (RPM) 2125 2125 2075 2075 2100 2125 2100 2100 2100 2100 2125 2125 2125 2100 2175 2175 2150 2150
Coolant Temp (°F) 196.2 196.2 196.2 196.2 196.2 194.9 194.9 194.9 194.9 194.9 194.9 194.9 194.9 194.9 194.9 194.9 194.9 194.9
Oil Temp (°F) 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 189.5 190.8 190.8
Manifold Air Tmp (°F) 89.6 89.6 89.6 89.6 89.6 89.6 89.6 88.2 88.2 88.2 88.2 88.2 86.9 86.9 86.9 86.9 86.9 86.9
A/C Pressure (PSI) 84 84 84 84 84 84 84 84 84 84 84 84 84 84 84 84 84 84
MAP Sensor (Volts) 0.78 0.78 0.8 0.8 0.82 0.78 0.82 0.8 0.8 0.82 0.82 0.82 0.76 0.78 0.78 0.78 0.74 0.74
Throttle Sensor (Volts) 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76
Throttle Angle (%) 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5
Battery Voltage (Volts) 13.6 13.6 13.5 13.5 13.6 13.6 13.6 13.6 13.6 13.6 13.6 13.6 13.5 13.6 13.6 13.6 13.6 13.5
Barometric Press (Volts) 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44
Left O2 Sensor (mVolts) 440 440 193 123 114 127 114 118 127 484 96 96 167 110 721 721 127 127
Right O2 Sensor (mVolts) 616 616 668 259 699 492 303 677 655 651 57 57 110 66 57 57 783 686
Block Learn Cell 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17
Left Block Learn value 133 133 133 133 133 133 133 133 133 133 133 133 133 133 133 133 133 133
Right Block Learn value 134 134 134 134 134 134 134 134 134 134 134 134 134 134 134 134 134 134
Left Integrator value 128 128 131 131 131 132 132 132 132 126 132 132 132 132 126 126 132 132
Right Integrator value 138 138 138 144 139 139 144 139 139 136 137 137 135 134 132 132 128 127
Left Inj Pulse (mS) 3 3 3.1 3.1 3.1 3.1 2.9 3.1 2.9 3.1 2.9 2.9 3 2.8 3 3 3 3
Injector Pulse (mS) 3.2 3.2 3.4 3.4 3.3 3.3 3.2 3.3 3.2 3.2 3.2 3.2 3.1 3.1 3 3 2.8 2.9
Mass Air Flow (gr/sec) 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15
CCP Duty Cycle (%) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Idle Air Mtr Pos (steps) 13 13 13 13 13 13 13 13 13 13 13 13 13 13 13 13 13 13
Learned Idle Pos (steps) 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10
Spark Advance (°) 36 36 36 36 36 36 36 36 36 36 36 36 36 36 36 36 36 36
Knock Retard (°) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Knock Sensor 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32
EGR Duty Cycle (%) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Vehicle Speed (MPH) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Engine Run Time (seconds) 122 122 123 124 125 126 127 128 130 131 132 132 133 134 135 135 136 137

I think that I have gotten some improvement, it seems to be running a bit better (as the numbers on the scan indicate). The next order of business is to swap the original injectors back in to the engine and see what difference that will make. I am keeping my fingers crossed.

Now, we are really getting close!

The left O2 sensor & the right O2 sensor readings are fluctuating as they should be.

The left block learn values & the right block learn values are similar as they should be.

The left integrator values & the right intergrator values are similar as they should be.

The left injector pulse width & the right injector pulse width are similar as they should be.

The temps of the converters, injectors and exhaust ports are evening out. All good!

Make the final checks as junk has described. If they check out fine, you now have an engine that needs to be driven on a road test.

As we discussed last nite: If you change out your fuel injectors and put your originals back in, you should have a fine running LT1 engine! That would be the safest bet until you decide how you want to upgrade your fuel injectors.

SAVE THE